This invention relates to apparatus for enabling the breathing of a patient to be assisted by means of a respirator. More specifically, the invention concerns a nasal cannula adapted to be connected between the nostrils of the patient and a hose leading to a respirator or other respiration assistance device.
Some patients having respiratory problems are assisted in breathing by a mechanical respirator which pumps ambient or oxygen enriched air directly into the lungs of the patient through a hose leading from the respirator, and an artifical airway at which the end of the hose opposite the respirator end, is terminated. Artificial airways known to the art include endotracheal tubes, tracheotomy tubes, and nasal cannulas. Unlike endotracheal tubes which are inserted into the trachea of the patient through the mouth and tracheotomy tubes which are inserted through an incision proximate the throat of the patient, nasal cannulas generally employ two hollow prongs adapted to be received in the nostrils of the nose of the patient and a tubular member in communication with the hollow prongs and the hose leading to the respirator.
Maintenance of the cannula in sealing relationship with the nostrils of the patient to prevent communication between the nostrils and ambient environment, and irritation of the nasal passages by the cannula are two problems encountered in the use of prior art nasal cannulas. These problems are aggravated upon movement of the head of the patient and are of particular concern when the patient is a neonate.
In order to overcome the problem of exposure of the nostrils to the ambient environment and resulting leakage, some prior art cannulas employ means for firmly impressing the nose against the cannula by outwardly expanding the nostrils thereby causing trauma and irritation. Some prior art nasal cannulas employ rigid prongs which are mounted on a transverse surface adapted to firmly engage the lip of the patient while the prongs are inserted into the nostrils to form an air tight seal. The use of such cannulas can result in extreme discomfort to the patient as well as the possibility of trauma and irritation within the nostrils, as previously described and to other skin surfaces of the patient.
Some prior art cannulas have addressed the problems of irritation and leakage by employing devices made of a flexible elastomeric or sponge rubber material to minimize irritation within the nostrils while forming an adequate seal thereabout. Still other prior art cannulas employ prongs having enlarged nasal end portions for forming an air tight seal with the interior engaging surfaces of the nostrils.
The use of soft and highly flexible rubber materials in nasal cannulas has an attendant disadvantage in that the prongs are likely to be compressed when bent during movement of the patient or stressed by the nostrils during breathing thereby obstructing the artificial airway through the prongs and interfering with instead of enhancing the patient's ability to breath. In prior art, cannulas which employ enlarged nasal end portions, the interface between the enlarged portions and the narrower tubular prongs generally forms a single point of weakness whereat stresses applied to the nasal cannula are likely to be concentrated thereby resulting in compression of or damage to the cannula. The problem of compression caused by movement is of particular concern when the cannula is used in a neonatal environment in which an infant's breathing is to be assisted by means of a respirator. Uncontrolled movement by the infant who cannot be alerted to the dangers of such movement is likely to result in bending of the prongs causing compression or pinching of the cannula. Interruption of or reduction in the oxygen enriched air administered to and the exhaled air withdrawn from the infant can cause serious harm to an infant whose breathing must be assisted by a respirator.
As a further means of preventing movement of the cannula within the nasal passages of the patient, numerous devices are known to the prior art for stabilizing the cannula with respect to the patient. Some devices employ the gas supply tubes which supply air from the respirator to the cannula for holding the cannula in place. For example, in U.S. Pat. No. 3,915,173 to Brekke, a cannula assembly is shown wherein portions of the gas supply tubes are seated on the bridge of the patient's nose. In U.S. Pat. No. 2,693,800, the gas supply tubes are passed over the ears of the patient. U.S. Pat. Nos. 2,168,705 and 2,245,969 also show mechanisms which are placed over the patient's ears. In U.S. Pat. No. 2,259,817, oxygen tubes are downwardly extended from a temple band encircling the head of the patient. The foregoing devices which are primarily designed for use with adults, employ substantially rigid supporting devices for the cannula device to maintain the position of the cannula with respect to the patient. The use of such rigid or semi-rigid devices to form a coupling between the cannula and a supporting skin surface on the patient is unsuitable for neonates who can be injured by such rigid devices upon abrupt movement.
Until the instant invention, there remained a need for a nasal cannula suitable for use with infants which was resistant to compression and damage cause by pinching of the cannula and which could be used with supporting means attachable to the patient for preventing the cannula from being dislodged from the nasal passages while precluding the possibility of injury to the neonatal patient during the patient's movement in the neonatal environment.